When Juan Manuel Santos dons the presidential sash Thursday it will mark the beginning of a four-year, high-wire political act that could bring an end to the hemisphere’s longest-running and deadliest civil conflict.

Santos, 62, a former minister of defense known for some of the most effective and controversial strikes against the nation’s guerrillas, is playing the role of peacemaker in an uneasy nation. While the country wants the bloodshed to end it’s also concerned about making concessions at the bargaining table.

Santos is also facing a feisty new opposition in the form of his old boss, ex-President Álvaro Uribe, who took a Senate seat last week and could play spoiler as an eventual peace deal is put up for referendum.

“The great challenge is peace,” Santos said recently. “And the next four years are going to be an enormous challenge for all of Colombia.”

As world leaders arrive for the inaugural ceremony, the country of 46 million has much to flaunt and some to hide. Over the last four years, the administration says it has pulled 2.5 million out of poverty on the back of an economy that is expected to grow 5 percent this year — among the fastest in the region. The country is also in the midst of a dramatic makeover, shedding its image as a dysfunctional drug haven and emerging as a hotspot for tourists and investors.

Even so, war simmers. Stung by previous peace efforts where rebels used lulls in fighting to regroup and rearm, the government has refused to consider a bilateral ceasefire even as it sits at the negotiating table with the Revolutionary Armed Forces of Colombia (FARC) guerrillas in Havana.

As a result, the FARC and the smaller National Liberation Army (ELN), which is expected to join the peace process soon, have been stepping up attacks on roads and infrastructure. The major port city of Buenaventura went almost 48 hours without power last week after electrical towers were destroyed. The country’s crude pipelines were attacked 64 times during the first half of the year, costing the country $460 million, the Colombian Petroleum Association told El Pais. Tanker trucks have been forced to dump their loads of crude into rivers.

That has rattled nerves in a nation that already has little faith in the guerrillas. A July poll by Datexco found that 61 percent of those surveyed do not believe the FARC truly want a peace deal; that’s up from 50 percent in June.

The attacks have also led Santos to issue some of his sternest warnings since talks began in October 2012.

“If you keep this up you’re playing with fire and this process can end,” he said recently. “Colombia’s patience is not infinite,” he added later.

Even so, most believe a peace deal will be signed in coming months. Negotiators have already reached agreements on three out of the six parts of the peace plan. A delegation of 60 victims, who have suffered at the hands of the guerrillas, the state and demobilized paramilitary groups, will be heading to Cuba soon. And as negotiators tackle the issue of how to deal with victims they’re also looking at the final points: ending the armed confrontation and verification mechanisms.

Cynthia Arnson, the director of the Latin America Program at the Woodrow Wilson Center, predicts “very rocky” times ahead as negotiators enter delicate territory.

“As they discuss the issue of victims of the conflict it’s inevitable that they will talk about questions of impunity for those who have committed war crimes and are responsible for gross human rights violations,” she said. “And that will be a very, very difficult issue as it is in any peace process.”

The real troubles may come once a deal is signed, said César Valderrama, the president of the Datexco polling firm. During his hard-fought reelection campaign, Santos often portrayed the peace agreement as silver bullet for the country.

“But the violence isn’t going to stop as soon as a paper is signed,” he said. Some guerrilla factions might not accept the deal, and violence might spike as drug and criminal gangs rush to fill the void left by the rebels.

“That could lead to frustration and make governing very difficult for Santos,” Valderrama said.

As Pinzón, a tough-talking minister, continues pummeling the guerrillas, Cardenas will have to keep the economy booming and continue to close the income gap – one of the sources of the conflict – even as the country faces a drought. For her part, Holguín, well respected abroad, will have to convince the international community to back a peace deal that some worry might run afoul of human rights laws due to its leniency.

Peace won’t be the only issue on Santos’ plate. Polls show that insecurity (driven by common crime), unemployment and healthcare are administration weak spots. And the country desperately needs better roads and ports as it hopes to remain competitive. Santos is also pushing reforms to eliminate reelection and instead have a single five or six-year presidential term.

Nelson Giraldo, a 60-year-old printer who works a few blocks from the presidential palace, said he fears the government may not be ready for peace. When right-wing paramilitary groups demobilized in 2004, many of them joined the ranks of criminal gangs known as the bacrim. He said he fears the same may happen with the thousands of guerrilla fighters who put down their guns.

“What’s the government going to do with all those kids?” he asked. “If they’re not careful, they’ll make gangs of their own or just be criminals on the street.”

But Giraldo also concedes how much the country has improved. Just 12 years ago, when Uribe first took office, guerrillas rained mortars down on the city center during his inauguration killing at least a dozen people. Few believe the guerrillas have the capacity or will to pull off an attack like that on Thursday, but Giraldo said it would be nice if the thought didn’t even cross his mind.